This invention relates to folding knives and in particular an assisted opening mechanism for folding knives.
Assisted opening mechanisms are popular features for folding knives due to their added utility and their improved safety and reliability over automatic or “switch-blade” type opening mechanisms. Folding knives typically include a blade pivotally connected to a handle, which allows the blade to rotate relative to the handle between an open position in which the blade extends from the handle and a closed position in which the blade is received within a corresponding recess within the handle. Assisted opening mechanisms typically include a bias member which moves the blade toward the open position when the blade is manually rotated from the closed position beyond a certain threshold point. Often times, the mechanism also applies a reverse bias in the closed position to hold the blade closed. Examples of the folding knives having assisted opening mechanisms may be found in U.S. Pat. No. 6,145,202; 6,338,431.
The present invention seeks to provide an improved assisted opening mechanism for folding knives, which helps hold the blade in the closed position, as well as, assists in moving the blade toward the open position. The assisted opening mechanism of this invention includes a bar spring seated within one of the handle sides and a contact pin extending from the blade. The bar spring is seated within a recessed cavity formed on one side of the knife handle. The contact pin extends outward from one side of the blade through an arcuate slot in the handle side and is position radially from the pivot axis of the blade so that the contact pin travels along the length of the acruate slot as the blade moves between its open and closed position. The contact pin rotates into engagement with the bar spring as the blade moves between the open position and the closed position, whereby the bar spring exerts a bias on the blade, which assists in moving the blade to the open position.
The assisted opening mechanism of this invention can be readily incorporated into folding knives of any conventional style, design or configuration, such as frame lock folders and liner lock folders and adds only two additional components to the basic folding knife design. The bar spring is completely enclosed and protected within one side of the knife handle. The bar spring only engages the contact pin and causes no material wear on the blade itself. The bar spring exerts no force on the blade when the blade is in the open position, but assists in holding the blade in the closed position until opening is manually initiated; consequently, the assisted opening mechanism does not affect the ‘lock-up” of the blade in the open position or the closed position.
The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings.